Thanks to both Boise Ed and Usual John for suggesting this one.
“First, why these questions? Is the guy on trial for credit-card fraud? Second, why is the judge wearing a ‘smoking jacket’ instead of judicial robes?”
Also of course “What’s the joke?”
Pardon my Credit Card
Comics I Don't Understand 
I was thinking that it’s a credit inquiry or credit check he’s being asked questions about his credit. Regarding the judge’s attire, maybe it’s an informal check?
Is the lawyer maybe going to go swipe said card and use it to make fraudulent purchases?
Powers has it. The lawyer is going to take that credit card.
I feel like there’s a “left my card in my other jacket” joke that didn’t quite take off. The judge’s robe may be a colorist error; if not, it baffles me.
The lawyer wanted to establish that he was a creditable witness.
“How much legal defense can you afford?”
The witness/defendant is wearing a jacket. Why would he leave his credit card in his (other) jacket at the table?
The judge’s jacket has some kind of fancy pattern on the lapel. Clearly not a judge’s robe, no matter the coloring.
I think Peter Burnett may have it. As for the judge, maybe he’s a justice of the peace who was awakened to do a wedding, and the lawyer said “As long as you’re awake–“
Dvandom has it. The guy’s own lawyer is asking the questions.
The judge was so impressed with Vinny’s suit in My Cousin Vinny that he went for something similar.
My first thought was aligned with what Powers said.
It might have been better, if this was the scenario intended, if there was a person at the defense table surreptitiously eying the jacket.
He is a man who has credit so he is good standing. He doesn’t overuse his credit so he is (not sure of term I am looking for – frugal is not correct, he does not overspend?) He has his card with him in his outdoor jacket (rain, cold weather) so he can prove this if the judge wants to run a credit check on him. Perhaps to cover his bail or to get him released in his cognizance or to establish him a trustworthy witness?